1. Field of the Invention
The present invention relates to a method of operating an engine upon occurrence of abnormal combustion, applied for a multiple cylinder gas engine, a multiple cylinder diesel engine or the like for power generation, which is capable of stepwise or continuously correcting a burning state through fuel regulation including fuel cutoff, in order to execute stopping or output limit operation of the engine, and also relates to an apparatus for controlling operation of an engine upon occurrence of abnormal combustion.
2. Description of the Related Art
A multiple cylinder gas engine or a multiple cylinder Diesel engine for power generation incorporates a protecting circuit for stopping the engine when abnormal combustion, that is, the so-called heavy knock, occurs in one or more of cylinders.
Specifically, in a conventional multiple cylinder gas engine (or a multiple cylinder Diesel engine) for power generation, when a cylinder pressure abruptly increases in one of cylinders, that is, the so-called heavy knock occurs, in a normal operating condition of the engine, the supply of fuel into all cylinders is cut off so as to stop the operation of the engine after a predetermined time elapses from the time of the detection of the heavy knock.
It is noted that a patent document 1 (Japanese Patent Laid-open No. 2005-69042) discloses measures for controlling operation of a gas engine upon occurrence of abnormal combustion, comprising a cylinder pressure detector for detecting a pressure in each of cylinders of the gas engine, and a combustion diagnosis unit for determining occurrence of abnormal combustion such as knocking, misfiring or the like in the engine cylinder in accordance with a detected value of cylinder pressure transmitted from the cylinder pressure detector, wherein when the combustion diagnosis unit determines occurrence of abnormal combustion, the injection timing of gas into the cylinder and the torch ignition timing are adjusted.
Further, a patent document 2 (Japanese Patent publication No. H2-11731) discloses measures for controlling operation of an engine upon occurrence of abnormal combustion, which is adapted to stop fuel injection from a fuel injector which causes an abnormality, and simultaneously stop fuel injection from a fuel injector associated with at least one cylinder which has a specific relationship with respect to a sequence order of a cylinder associated with the abnormal fuel injection, thereby it is possible to prevent the engine from stopping upon occurrence of abnormal combustion.
In a conventional multiple cylinder gas engine (or multiple cylinder Diesel engine) for power generation, as stated above, when heavy knock occurs in one of cylinders in a normal operating condition, the supply of fuel into all cylinders is cut off so as to stop the engine after predetermined time elapses from the time of detection of the heavy knock. That is, in the above-mentioned conventional technology, the engine merely comes to a stop after the detection of occurrence of heavy knock in order to protect the engine.
Further, the patent document 1 discloses no more than the measure for adjusting the injection timing of gas into a result of cylinder and the torch ignition timing in accordance with a determination of occurrence of abnormal combustion such as knocking, misfiring or the like in the engine by the combustion diagnosis unit. That is, no consideration is made for the control of operation of fuel cutoff of an engine in view of occurrence of heavy knock in one of cylinders of the engine.
The patent document 2 fails to disclose any measures other than measures for stopping fuel injection of a fuel injector which causes an abnormality and for simultaneously stopping fuel injection of a fuel injector for a cylinder having a specific relationship with the sequence order of a cylinder associated with the abnormal fuel injector. That is, no consideration is made for detailed control for operation of fuel cutoff of an engine upon occurrence of abnormal combustion.